I too am using the sc_trans_linux but unfortunately it does not support relaying right now (from what the config says). In order to stream two feeds at different bandwidths of the same content you would have two instances of the sc_serv program running with DIFFERENT config files. You could use say 128k.conf and 56k.conf. When you load each instance of the sc_serv program up you will load them like this:
The nice thing about this is when you do a 'ps ax' to list the processes they will show up like this:
31937 ? S 0:00 ./sc_serv 128k.conf
See? Easily recognizable. Remember that those two config files/servers must run on DIFFERENT ports. So use something like 8080 and 8082 or something like that. Remember too that Shoutcast uses two ports (in and out). The second step to this is to create two config files for your sc_trans_linux program. This is where you obviously setup your bitrates and such (you should know this). You can do the same for the config files, just name them 128k.conf and 56k.conf and run the program with the respective files.
It will show up in your process as the following:
15376 ? S 0:00 ./sc_trans_linux 128k.conf
But like I said... sc_trans_linux currently does not support relaying but I *hope* it does (hint hint :P) Right now I'm looking at another piece of software called IceCast that supposedly supports that. Unfortunately it adds a THIRD program into the mix though. I wish it was easier for us Linux users! lol...